Organic electronic devices play an important role in industry. For example, organic light emitting diodes (OLEDs) are promising for display applications due to their high power conversion efficiency and low processing costs. Such displays are especially promising for battery-powered, portable electronic devices, including cell-phones, personal digital assistants, handheld personal computers, and DVD players. These applications call for displays with high information content, full color, and fast video rate response time in addition to low power consumption. OLED's typically contain electroluminescent (EL) layers arranged between an anode and a cathode. Each EL layer contributes to the overall performance of the display. Thus, when manufacturing a display containing an OLED, each EL layer is carefully deposited in a controlled fashion onto a suitable underlying surface.
One cost-efficient method for deposition of EL layers in the manufacture of such displays is solution deposition. Solution deposition typically involves depositing a layer from solution using a variety of well-known techniques, such as, e.g., spin coating and ink-jetting. In certain devices, the electrically conductive polymers or other organic charge transporting materials are used. During the manufacture of the organic electronic device, the layer of the organic materials using solution processing techniques to create the device can create challenges. In particular, it is not unusual for the solvent(s) used to dissolve certain of the device's organic charge transport materials (e.g., whether photoactive, emissive, hole transporting or electron transporting) and also do not permit good deposition during manufacture in that the solution may not wet or spread sufficiently over the layer onto which it being deposited. As such, one area currently drawing the attention of researchers is the identification of solvents for optimum solution deposition properties, which in turn results in cost-efficient production of devices containing OLED displays.
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